Joining the table itself called self join. Self join is
used to retrieve the records having some relation or similarity with other
records in the same table. Here we need to use aliases for the same table to
set a self join between single table and retrieve records satisfying the
condition in where clause.

@shashikant...Actually here suresh is manager for two employees and prasanthi is manager for other two employees that's why you are getting two times. please use DISTINCT in your query like as shown above.